DESCRIPTION: (Applicant's Description) Prostate cancer is the most commonly diagnosed cancer and ranks as the second leading cause of cancer death among men in the United States. For these reasons, there has been great interest in the use of prostate cancer screening tests such as the prostate-specific antigen (PSA) test. Though the PSA test is highly sensitive in identifying early malignancy, and some professional organizations recommend PSA screening in men 50 years and older, no controlled studies have yet been published that address the efficacy of this test in reducing mortality due to prostate cancer. The proposed study is a population-based case-control design to assess the efficacy of PSA screening in reducing the risk of death due to prostate cancer. The study population will consist of male members of the Kaiser Permanente population in Northern California. Cases will include male enrollees aged 50-84 years who died of prostate cancer between 1997-1998 (n~300). For each case, one control will be randomly sampled from the male Kaiser population and matched on year of birth, race and years of membership the date of the case's diagnosis (n~300). Medical records of cases and controls will be reviewed for the receipt of PSA screening and for other information relevant to the occurrence of prostate cancer (i.e.-history of vasectomy and benign prostatic hyperplasia). Cases and controls will be compared for the receipt of screening during periods of time that correspond to the tumor's detectable, preclinical phase, adjusting for confounding as necessary. This study has the potential to provide valid information regarding the presence and size of the benefit from this controversial, but possibly important, screening strategy.